IGBT (insulated gate bipolar transistor) is a composite full-controlled type of voltage-driven power semiconductor device composed of BJT (Bipolar Junction Transistor) and MOSFET (Metal-Oxide-Semiconductor-Field-Effect-Transistor), which combines the high input impedance characteristics of MOSFETs with the low-saturation-voltage capability of BJT. The IGBT exhibits the feature of high frequency, simple control circuit, high current density, and low on-state voltage, such that it is widely applied to the power control field. In the real practice, the IGBT is rarely used as an independent device, especially under conditions of inductive load, the IGBT requires a fast recovery diode freewheeling. Therefore, the conventional insulated gate bipolar transistor products usually employs a FWD (freewheeling diode) connected in parallel to protect the IGBT. In order to save the cost, the FWD can be integrated into the IGBT chip, thus forming the IGBT with a built-in diode.
In the prior art, the manufacturing of the conventional IGBT with the built-in diode usually employs two backside photolithography techniques, so as to form the spaced N+ region and the P+ region by selectively implanting and diffusing, and the N+ region and the P+ region are distributed on the whole backside region of the IGBT including the active region and the terminal protection area, which results in a poor recovery characteristic of this type of IGBT with the built-in diode.